[Standards] <[CDATA[ in XMPP

Robin Redeker elmex at x-paste.de
Mon Jul 30 23:30:03 UTC 2007


On Mon, Jul 30, 2007 at 04:48:53PM -0600, Peter Saint-Andre wrote:
> Robin Redeker wrote:
> > If we don't call something XML which clearly is not XML, then there
> > aren't any further confusions possible.
> > 
> > But still the term 'XML' is quite often used in the XMPP specs.
> 
> Interestingly, the first paragraph of the XML specification says:
> 
> ***
> 
> Extensible Markup Language, abbreviated XML, describes a class of data
> objects called XML documents and partially describes the behavior of
> computer programs which process them. XML is an application profile or
> restricted form of SGML, the Standard Generalized Markup Language [ISO
> 8879]. By construction, XML documents are conforming SGML documents.
> 
> ***
> 
> Is it true that "XML is SGML"? Obviously some SGML pedants would object
> because XML is "an application profile or restricted form of SGML". Yet
> "XML documents are conforming SGML documents"! So here we have a rough
> definition of conformance, and a working example since XML conforms to SGML.
> 
> Similarly, a complete XMPP session (with start and end stream tags) is a
> conforming XML document. Just because the session does not include
> comments, processing instructions, DTD subsets, entity references other
> than those predefined in the XML spec, other other restricted features
> does not mean that the session is not an XML document.
> 

The difference is, which I consider the major confusing part for
developers, that the XML recommendation doesn't always use the term
'SGML' when defining something. The XMPP spec very often uses 'XML' to
describe things.

> So we could say this in rfc3920bis:
> 
> ***
> 
> The Extensible Messaging and Presence Protocol (XMPP) defines a class of
> data objects called XML streams as well as the behavior of computer
> programs that process XML streams. XMPP is an application profile or
> restricted form of the Extensible Markup Language (XML). A complete XML
> stream (including start and end stream tags) is a conforming XML document.
> 
> ***

Sounds nice.

> > (Please take this mail as serious as you like, I don't know how serious I mean it.)
> 
> Don't worry, I take all of your emails that way. :P

Just take care that some mails have the intend to point something
out, which I would like to have fixed or I really feel could
make the life of other developers easier. I of course can only offer an
opinion w.r.t. technical aspects of some things.

That some things can't be fixed because of backward compatibility is
unfortunate. But other things (still) can, just make sure to take at
least those serious "enough" :-)


R



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